by Robin A. Webb, USA TODAY

The tape, provided to CNN, allegedly contains audio captured during a Ferguson resident's video chat at the time of the shooting. CNN says the authenticity of the tape has yet to be verified, but what appears to be gunfire can be heard in the background of the call.

As many as 10 shot-like sounds can be heard. Several shots are fired in what appears to be fairly quick succession. There is a brief pause, then more shots are fired.

An autopsy concluded that Michael Brown, 18, was shot six times, with two fatal shots to the head. The Ferguson officer involved has been identified as Darren Wilson, 28.

Law enforcement officials and bystanders have provided differing accounts of what led to the fatal encounter. Police say Wilson stopped Brown and a friend for walking in the street, asking the two to move to the sidewalk, and words were exchanged. According to Wilson's account, he was attacked by Brown as he attempted to exit his cruiser and the two scuffled for the officer's gun inside the car.

Both Wilson and witnesses concede Brown took off running. The witnesses say the officer fired on the unarmed teen as he had his hands up to surrender. Wilson supporters say Brown was bull-rushing Wilson, who shot Brown in self-defense.

The shooting ignited racial tensions, sparking several days and nights of protests, riots, looting and unrest.

Brown's funeral service was Monday, and the case is currently being presented to a grand jury. Attorney General Eric Holder has promised a thorough investigation.

The organization Black Lawyers for Justice plans to file a $200 million class action lawsuit against Ferguson authorities Tuesday, KDSK-TV reported. According to the organization's website, the group's mission is to fight police brutality.

A press conference is set for 1 p.m. CT Tuesday at the U.S. District court building in St. Louis.